[Amps] toroid tank coil heating up

[John Keating]

My 2 x 3-500Z amp uses a two-stack T-225A-2 red mix iron powder toroid for 160-80-40. It gets hot, especially on 160, changing the loading and causing the grid current to drift up on extended transmission. This is not a new phenomenon, but I thought I would ask the experts if there is a remedy, perhaps other than using a triple stack or going to an air core coil, neither of which I have room for.

John
AI6LY